Cold Spell Discussion (19/12/09) (Band of Sleet to Snow to push south)

munsterlegend

Weathercheck wrote: »

Because current projections would suggest abit of rain then a lashing of snow but probably only amounting to a a small dusting for most that will just turn to ice later on.

However these cold front passages are notoriously difficult to forecast and you can only give a guide as to how they will act.

Look at the satellite pics and hope to see it really exploding to live over the coming hours with a definite tight shape to it.

just listening to the met eireann forecast there and they gave an inkling it may turn to snow as the temperature plummets. also accumulations of 3 to 8 cm in ulster/connacht and west munster over night - cork might just might get something!

maquiladora

munsterlegend wrote: »

just listening to the met eireann forecast there and they gave an inkling it may turn to snow as the temperature plummets. also accumulations of 3 to 8 cm in ulster/connacht and west munster over night - cork might just might get someting!

Cork could do well from the showers Sunday/Monday.

john 1994

i hope munster get some snow tonite :D:D

fricatus

Deep Easterly wrote: »

Hehe, winter lurker here, don't normally post since I don't know what I'm talking about, but that's just a classic!

ROFL

Elmer Blooker

All the precipitation is over Scotland, **** all heading our way.
Am I disappointed? not really, I wouldn't expect anything from a northerly where I live.
With an area of low pressure over the country during the next few days I think we will see a gradual rise in temperature as the Arctic airflow is cut off and the warm influence of the Atlantic takes over.
Christmas day: cloudy and around 6c.

nacho libre

maquiladora wrote: »

National Forecast




Very cold tonight with a severe frost. Occasional hail and snow showers also, chiefly in Connaught, Ulster and west Munster with some accumulations of snow likely. Minimum temperatures of 0 to -4 degrees leading to icy stretches.

http://www.met.ie/forecasts/

when met eireann use the word "Occasional"-

i wonder does that mean showers every hour or so lasting about 10-15 minutes. i would prefer if they said frequent and prolonged showers overnight resulting in snowdrifts by morning.

Deep Easterly

nacho libre wrote: »

when met eireann use the word "Occasional"-

i wonder does that mean showers every hour or so lasting about 10-15 minutes.

No set criteria for the use of the word "occasional". Although my experience of occasional showers is one of fairly moderate frequency but loads of dry slots inbetween.

nacho libre

Elmer Blooker wrote: »

All the precipitation is over Scotland, **** all heading our way.
Am I disappointed? not really, I wouldn't expect anything from a northerly where I live.
With an area of low pressure over the country during the next few days I think we will see a gradual rise in temperature as the Arctic airflow is cut off and the warm influence of the Atlantic takes over.
Christmas day: cloudy and around 6c.

yes i suppose if it doesn't snow in dublin it's really a non-event.

normally an arctic airflow tends to be cut off after a day or two anyway with any snow showers turning sleety thereafter on lower ground. to be honest one day of snow(between tonight and part of tomorrow) is all i'm really expecting out of this.

WolfeIRE

Don't be too disappointed. One of the primary reasons for the downgrade is huge uncertainty. I am certain there will be snow in many places over the next 12-24hrs. ME are being hugely cautious and they are prob right. They do not like to speculate like we most of us do. Heads up guys:cool:

Latest from Irish Times website

Motorists warned over cold snap

Motorists have been warned this weekend will be the coldest of the year with overnight temperatures plummeting as low as minus five degrees.
All parts of the country could see falls of snow this weekend as showers from the north turn to snow especially on high ground.
Met Éireann said temperatures will fall quickly this evening with sleet or snow showers and icy stretches expected.
There will be a severe frost overnight with minimum temperatures of 0 to -4 degrees and the freezing temperatures are expected to continue into the middle of next week.
“Anywhere could a snow shower this evening and tonight,” said Met Éireann forecaster Joan Blackburn.
Connacht and Ulster and west Munster are likely to get the worst of any snowfall in the coming days with the likelihood of falls increasing in inland areas.

ninebeanrows

Elmer Blooker wrote: »

All the precipitation is over Scotland, **** all heading our way.
Am I disappointed? not really, I wouldn't expect anything from a northerly where I live.
With an area of low pressure over the country during the next few days I think we will see a gradual rise in temperature as the Arctic airflow is cut off and the warm influence of the Atlantic takes over.
Christmas day: cloudy and around 6c.

Do you have a radar cover the area where the western part of the front is or something!!? Relax

maquiladora

Is that a band of stronger precipitation building up there to the west of the Faroe Islands? http://www.sat24.com/Region.aspx?country=gb&sat=ir&type=loop

lucernarian

I've been carefully looking at satelite footage so far. It's clear that there is front occlusion taking place. But west of Scotland isn't clear, particularly because of the lack of radar and whatnot.

I still think that the temperature gradient isn't there. I took a low-lying coastal west Scotland met office station as an example. http://www.metoffice.gov.uk/weather/uk/he/skye_lusa_latest_weather.html

At a place where northerly winds have established in the front (indicating cold frontal occlusion), the temperature has fallen 2 degrees and it's still raining. I've checked other stations and the drops are a bit bigger on average (inlands but westerly are best examples are best examples) and it still shows a drop of 4 degrees at most.

I also see that the UKMO have issued no alert for NI, unlike what they have done for the border region in Britain.

munsterlegend

temperature here is 4.5 degrees. when the precipitation reaches down here(if it does) it should be a good bit colder so it may turn to slow perhaps?! clutching at straws maybe but at least there is a chance.

WolfeIRE

maquiladora wrote: »

Is that a band of stronger precipitation building up there to the west of the Faroe Islands? http://www.sat24.com/Region.aspx?country=gb&sat=ir&type=loop

looks like it. Long way to travel to reach us yet though.

ninebeanrows

Here is the cold front

ninebeanrows

To_be_confirmed wrote: »

I've been carefully looking at satelite footage so far. It's clear that there is front occlusion taking place. But west of Scotland isn't clear, particularly because of the lack of radar and whatnot.

I still think that the temperature gradient isn't there. I took a low-lying coastal west Scotland met office station as an example. http://www.metoffice.gov.uk/weather/uk/he/skye_lusa_latest_weather.html

At a place where northerly winds have established in the front (indicating cold frontal occlusion), the temperature has fallen 2 degrees and it's still raining. I've checked other stations and the drops are a bit bigger on average (inlands but westerly are best examples are best examples) and it still shows a drop of 4 degrees at most.

I also see that the UKMO have issued no alert for NI, unlike what they have done for the border region in Britain.

I think the MetO are using a case of warn for whats happening now for the front.

I think taking the Isle of Skye as an example for it not snowing ain't the best either Just a tad exposed!

nacho libre

it's got digustingly mild(6c) now. i doubt there will be sleet or snow from the back edge of the front here.

maquiladora

nacho libre wrote: »

it's got digustingly mild(6c) now. i doubt there will be sleet or snow from the back edge of the front here.

8c here!

Scubadevils

It may have been mentioned already but I see a slight change from the met in terms of their view on Christmas day...

The cold weather is going to continue next week with further severe night frosts and wintry showers. Sunday night: Very cold with a mixture of clear spells and heavy hail, sleet and snow showers. Again the showers will be chiefly in the southwest, west and north with some accumulations of snow occurring; scattered snow showers will affect the midlands; the east and southeast will be mainly dry - however some snow showers will occur through here as well. Lowest temperatures zero to -5 degrees with a severe frost and icy stretches Sunday night and Monday morning. Monday: Very cold with sunny spells and scattered heavy hail, sleet and snow showers. Frost and icy stretches Monday night. Tuesday and Wednesday: still very cold with night frosts and icy stretches. There will be sunny spells during the day but a scattering of heavy wintry showers also. Christmas Eve and Christmas Day: Still likely to be cold with frosts and icy stretches and a further possibility of wintry showers but the details are still uncertain (as of Saturday morning).
http://www.met.ie/forecasts/

Scubadevils

Weathercheck wrote: »

Here is the cold front

So the band ahead of that is the rain/sleet mix? - Which will be heavier than the cold front in terms of precip?

Deep Easterly

Felixdhc wrote: »

It may have been mentioned already but I see a slight change from the met in terms of their view on Christmas day...

That is an interesting forecast. It is also interesting to note that the latest ECM models has the potential to bring a lot of snow early Christmas morning. Although given the instability of the set up at present, it is all to play for as they say, but could be one to watch.

lucernarian

The Met Office station on Stornoway has temperatures of 1.5 degrees. It's in a coastal area but they are the places where the effects of the air modification can be best seen. This front won't have snow except on its back edge for any part of Ireland. It would be wrong to use these examples if most of Ireland wasn't already under a nearly saturated >4 degree air mass. In proper artic conditions, snow should be at least able to fall at a coastal area even if it may not stick.

Some of that black line isn't cold front per se. The triple point on that map is actually in central Scotland.

Scubadevils

Deep Easterly wrote: »

That is an interesting forecast. It is also interesting to note that the latest ECM models has the potential to bring a lot of snow early Christmas morning. Although given the instability of the set up at present, it is all to play for as they say, but could be one to watch.

Another roller coaster week so... is ECM on its own with that potential at the moment?

Deep Easterly

maquiladora wrote: »

8c here!

Just 5c here, rising a little though. Air has a crispy frosty look to it but can see big banks of cloud moving down from Mayo.

Deep Easterly

Felixdhc wrote: »

Another roller coaster week so... is ECM on its own with that potential at the moment?

To be honest, I have no idea, haven't really looked at the other models today. On vodafone "broadband" here at the moment at it is absolutely crap for viewing charts.

Scubadevils

Deep Easterly wrote: »

To be honest, I have no idea, haven't really looked at the other models today. On vodafone "broadband" here at the moment at it is absolutely crap for viewing charts.

Just had a look over on NW and it would seem it is.

I really must learn how to read the charts and not rely solely on reading posts on NW!!!

Deep Easterly

Felixdhc wrote: »

Just had a look over on NW and it would seem it is.

I really must learn how to read the charts and not rely solely on reading posts on NW!!!

There is a new thread here on the weather forum that deals with how to read weather charts. Once you get the knack, it all becomes second nature!

patneve

Sun is out now in Dalkey, wind was from west now from SW, dew point on the rise. Air temp 3,6 degrees. Obviously anything that will fall this evening will initially be rain, but I am confident of some back edge snow: we will go from a -3/-4 at 850 to a -8 at 850, there HAS to be precipitation...time will tell anyway

nacho libre

Deep Easterly wrote: »

To be honest, I have no idea, haven't really looked at the other models today. On vodafone "broadband" here at the moment at it is absolutely crap for viewing charts.

i'd be more confident when ecm is progging that as they tend to be more reliable than the gfs, and the other models tend to follow their lead. still, in saying that they could easily do a 360 on the next run.

meanwhile:
http://www.raintoday.co.uk/

munsterlegend

To_be_confirmed wrote: »

The Met Office station on Stornoway has temperatures of 1.5 degrees. It's in a coastal area but they are the places where the effects of the air modification can be best seen. This front won't have snow except on its back edge for any part of Ireland. It would be wrong to use these examples if most of Ireland wasn't already under a nearly saturated >4 degree air mass. In proper artic conditions, snow should be at least able to fall at a coastal area even if it may not stick.

Some of that black line isn't cold front per se. The triple point on that map is actually in central Scotland.

whats your view on the shower front activity behind with the cold air? will it be a northern event only?